"Pulse" Storms Make For Gorgeous Summer Skies

A small, isolated storm formed over the Adirondacks around
sunset last evening, as seen looking toward the southwest
from St. Albans, Vermont. 

One of the many things I like about summer is the sky is far more interesting and beautiful than in the winter.

Summer is the time of year when scattered showers and thunderstorms are more likely, without those dreary, boring overcast skies that come in the colder seasons.

Such was the case last evening when isolated thunderstorms erupted over mountainous terrain of northern Vermont and the Adirondacks of New York.

These dramatic looking, but usually harmless and brief thunderstorms often form during these hot, humid days.

There's really no weather systems to create updrafts that would form organized lines of clusters of long lasting storms.    But the atmosphere in these conditions is primed for storms, if only there were a trigger.

That trigger is the mountains. The strong June sun helps creates updrafts that also help cause light local breezes.  If things line up just right, one of these breezes hits a mountain slope and is forced to rise.

That breeze going up the side of a mountain can be just enough to trigger a storm.  That upslope breeze becomes a rapidly rising column of air, which forms almost immediately into a towering thunderstorm, the kind we saw here and there last evening. They go from nothing to immense, often in just minutes

Since these clouds are so tall, they can be seen from very far away. People in the Burlington area saw a gorgeous white tower erupt to the northeast early Friday evening. That storm was near Greensboro, almost 50 miles away as the crow flies.

Beautiful isolated storm last evening in
northern Vermont. Photo via Twitter
by Charlie of Mystery Springs
@SlowWaterMvmnt

Unlike in some hot spells, when haze obscures the best views, the skies Friday were more clear, making the beautiful storms more striking.  They were isolated, so looking east, the low angle sun turned the clouds brilliant white, surrounded by a deep blue background.

Some lucky bastard up near Greensboro was probably treated to a brief downpour for their garden, and maybe a lightning strike or two.

These so-called "pulse" storms die pretty much as fast as they form.  Remember, there's no real weather system, or cold front, or boundary to continue the updraft.

Once they move beyond that mountain that caused the initial updraft in the first place, the storm collapses. The process from initiation to dissipation can take less than an hour.

I did say these pulse storms are usually harmless. But there is one moment - when they're dying - when they can become momentarily dangerous.  The storm collapses, often in a very localized gush of wind and heavy rain.

This collapse could become a very local microburst, in which wind is strong enough to cause damage in a very small area.  One end of a street might have fallen trees from this type, while a mile away, there was just a gentle breeze.

Timing out these collapses is hard, and since they're so local and quick, they're often over and done with by the time the National Weather Service can issue a storm warning.

On some occasions, a pulse storm can keep forming in the same location all afternoon and evening, and just not move. In those cases, you can get a small area of dangerous flash flooding while immediate surrounding areas remain dry.

These two hazards only sometimes happen. More often than not, a pulse storm will quickly collapse and die with no danger involved. That's why they're called pulse storms. They quickly form, then quickly fade. It was just a quick pulse.

After we lost the Greensboro storm last evening, a couple others formed in the Adirondacks, contributing to a gorgeous sunset as the orange light lit up the towering clouds to our west and south.

If you missed these beautiful storms last night, not to worry. The weather pattern is kind of stuck in this hot, humid, still and featureless set up.  This will favor more scattered, slow moving and brief "pulse" storms today, Sunday and Monday.

They tend to start forming in the early to mid afternoon on these hot days, and fade with the setting sun.  The storms tend to avoid large valleys, so we in the dusty Champlain Valley will just be bystanders, begging in vain for just a little rain from these brief showers.

A weak cold front will approach us during the upcoming mid to late week.  That will provide enough forcing for more sustained, and somewhat more widespread showers and storms starting perhaps on Tuesday and continuing into Wednesday.

Here We Go Again: Distant Wildfire Smoke Hazing Up Our Skies

Smoke from wildfires in Alberta gave a brassy hue to
the evening skies over St. Albans, Vermont Thursday. 

Did it seem hazy to you here in Vermont yesterday afternoon?

You were on to something. Smoke from wildfires in Alberta was high overhead, introducing yet another summer in which clear blue skies are marred by smoke.

To be fair, Thursday wouldn't have been a pure bluebird sky day anyway. High and mid level clouds were coming in ahead of a cold front that was to our north and a storm system scooting by to our south.

But smoky haze gave a brassy hue to the atmosphere, especially yesterday evening. With a northwest flow aloft occasionally coming through over the next week, I wouldn't be surprised if we have other hazy days.

It still seems sort of hazy out there this morning behind that cold front.

It's not just us. Those Alberta fires are pushing smoke into much of the United States. Smoky skies have affected much of the northern Plains states  and southern Canadian prairies as well.

The smoky skies have been occasionally spreading to far-flung places like Vancouver, Minneapolis, Toronto, Detroit and Kansas City.  Smoke has also been spreading north to the Arctic Circle and into northeastern Alaska. There's a great smoke map that allows you to track the smoke by hitting this hyperlink. 

The fires up in Alberta are huge and out of control. At least 10,000 people in the remote region have been evacuated, and there's little sign that they fires will be under control any time soon.

Wildfires do seem to be on the increase and the season is lasting longer, due in large part to climate change. Unfortunately, we've had to get used to hazy, smokey skies in recent years as large fires repeated pump smoke into the atmosphere.

Springtime wildfires in the North are increasing because the snow melts earlier in the season, things dry out faster so fires can start. There have also been substantial wildfires in Siberia this spring.

While the smoke is rarely dense enough in Vermont to cause health problems, any level of particulate pollution in the atmosphere isn't good for us.

Mostly, it's just a let down when you want a brilliant blue sky and you get a sickly haze. It's not that we won't have bluebird days this summer or in future summers. It's just that we'll have to get used to experiencing fewer of them.

On the bright side, I suppose, the wildfire smoke can create more colorful and interesting sunrises and sunsets. You always have to find the positive somewhere, right?

Aurora Borealis Was Widespread Last Night. Did You See Any Of It

The International Space Station caught this
view of the Northern Lights last night.  

A large geomagnetic storm from the sun set off incredible displays of aurora borealis across much of the Northern Hemisphere, and parts of the Southern Hemisphere, both Monday night and especially last night.

Monday night, much of New Zealand was treated to the spectacle.

Last night, much of Northern Europe, including Britain, and North America, including pretty much all of the parts of Canada that had clear skies, and much of the northern United States got the great sky show.

The view of the Northern Lights from Yellowknife, Northwest
Territory, Canada last night. By Yuichi Takasaki  

This was probably the most intense electromagnetic storm in the past several years, even stronger than the one last September that also caused spectacular shows.

As EarthSky.org notes, these geomagnetic storms, outbursts from the sun really, send lots of charged particles which bombard the Earth's upper atmosphere if the sun's outburst is aimed at us.

This causes electrons in the upper atmophere to go into a higher energy state.

When the electons get over this excitement and revert back to their lower energy, they release a photon, otherwise known as light.  

Saginaw, Minnesota last night. Photo by Mark Tarello
via Twitter @mark_tarello.  

Of course, there are zillions of electrons up there, so when a whole bunch of them get together and release those electrons, you get the type of aurora borealis a lot of people saw last night.

If these space storms are super intense, the can disrupt power grids on Earth. In fact some scientists say a really bad one could cut electrical power to much of the Globe for weeks or months.

Imagine how disruptive that would be.

Nothing that bad has happened yet in modern times.

Sweden last night. Via Twitter, @AndersJilden. 

But an intense geomagnetic storm cut electrical power to pretty much the entire Canadian province of Quebec in March, 1989 for 12 hours. There have been smaller scale power outages in the United States caused by this.

This geomagnetic storm wasn't intense enough to screw up power grids. But it did give us quite a show.

Here in Vermont, it was kind of cloudy, but there were occasional clear moments. I saw a kind of a green, flickering haze near the northwest horizon as I took the dogs outside at around 4 a.m. today.

And there are nice photos and videos coming in from people who were watching the sky from on or near Lake Champlain.

Malletts Bay, Colchester, Vermont. Photo by
Dan Russell.  

It's hard to say whether there will be another show tonight, but the geomagnetic storm has peaked, so a display as widespread as last night's is unlikely.

I've also got a couple videos, below to show what happened last night.

The first is a largely unedited series of time lapse images of the aurora over southern Saskatchewan, Canada:




Another time lapse, this one by Dan Russell o Northern Lights Now, over Malletts Bay, Lake Champlain, Colchester, Vermont:

More On Those Photogenic Thursday Skies

The first good thunderstorm of the day blossoms
over Lake Champlain, west of South Burlington
Vermont late Thursday morning.  

Thursday was arguably the best day of the summer for sky watching in New England, especially for weather geeks.

We had the perfect combination of a lack of haze for good visibility, and lots of rapidly developing, and rapidly disappearing showers and thunderstorms, which made for a sky you could watch and see change from one minute to the next all day.

You might have seen my post from last night that showed a small cloud turning into a thunderstorm within 20 minutes.

Some of the storms were briefly strong, producing some hail and gusty winds, but this wasn't a widespread severe outbreak.  Still, there were several reports of quarter sized hail in southern New Hampshire and coastal Maine, and Saratoga County, New York got hit with damaging winds.

Smaller clouds being drawn
up at an angle into the top
of a larger storm around noon Thursday
in western Vermont.  

There was a pool of cold air high overhead in New York and New England. The contrast between the upper level cold, and the heated ground from the warm August sunshine between the clouds, kept the storms churning all day.

There wasn't much humidity in the air, so the downpours weren't super intense, though a couple places got a fair amount of rain because they were hit repeatedly by storms.

Still, you could watch the storms blossom, then, given their lack of moisture supply, you could watch them rain themselves out and dissipate just as fast as they could form.

It was so hit and miss. While working outside in South Burlington, Vermont yesterday, I saw a storm blossom and start heading toward me. I could see the downpour gushing from the base of the cloud.

But as the storm got near, it rained itself out. There were just sprinkles where I was.

When I drove two miles down the road a bit later, you could see lots of puddles and mini-brooks running along the curb, a testament to the heavy downpour the brief storm created.

A late day thunderstorm greets commuters along
Interstate 89 in St. Albans, Vermont Thursday.  

The cold air pool high above us is moving away now.

We'll get some great weather the next few days in New England: Sunshine, warmth and humidity that's reasonable. Great for the beach or whatever else you want to do outside this weekend.

If you're looking for one of those "wait a minute and the weather will change" days, like yesterday, it ain't happening.

Haze Clears In Vermont, Northeast, For Now; Could Be Back

That spell of very warm, humid weather that ended with Thursday's showers and thunderstorms also brought a lot of haze to the Northeast.

Haze over Lake Champlain
in this view from South
Burlington, Vermont.  

As I start my day now, on Friday in St. Albans, Vermont, the sky is very clear. There's no haze,  and it's bright blue and beautiful.

Clean air from Canada is the reason for the improved atmosphere. Northwest winds are drawing the air into our neck of the woods.

The haze might come back though. As we start heading into Sunday and especially next week, the air flow over us will come more from the west.

As you know, huge wildfires continue to plague the west, especially in California.  Smoke from the fires could make it this far, in the form of haze, just as it did earlier this week.

Any haze we do get won't be just smoke from the fires.  As is often the case during warm spells in the summer, it gets hazy with or without fires out west. We also get pollutants from Midwest industries.

The particles from the pollution, be it industry in Cleveland or forest fires in the Sierra Nevada, cling to water droplets, and we get hazy.

It's hard to say how hazy it will get, or even if the landscape will get particularly blurry. We'll just see how it plays out. Meanwhile, enjoy the wonderful clear air today and Saturday.